If you've ever accidentally closed a tab with something important in it, or shut down the browser only to realize you needed one more bit of information about the webpage you were reading, despair not. Google Chrome remembers the last ten tabs or windows you've closed, and lets you restore them. You can get at these in several ways:

On the bottom of New Tab page, the most recent few are listed in the "Recently closed" section. You can even use this after restarting the browser, in case you accidentally quit with something important open.

If you right-click in the tabstrip, you'll see an option to "Reopen closed tab" or "Reopen closed window", depending on what you last closed. Using this repeatedly goes back through the remembered tabs and windows, from most to least recent.

If keyboard shortcuts suit you more than context menus, just use ctrl-shift-T to reopen a close tab or window.